1. Field of the Invention
This invention provides a sound source system capable of producing a desired coverage pattern with a high sound pressure level that may be steered towards a desired listening area.
2. General Background and State of the Art
In sound reinforcement applications, a sound source that produces an effective high sound pressure level (SPL) may be desired at low frequencies. This is often accomplished by forming an array of sound sources that are stacked together to increase the SPL. As each of the sound sources in the array generate sound, they add to generate a main lobe of sound energy, and depending on how the array is configured, other side lobes of sound energy may be generated as well. The main lobe and the side lobes of sound energy form a coverage pattern of sound energy that has increased SPL on axis, however, the main lobe of energy may become excessively narrow and the side lobes may be undesirable.
As the array increases in size, the coverage pattern may become narrower. For example, a taller array will generally have a narrower vertical coverage pattern than a shorter array. And a wider array will generally have a narrower horizontal coverage pattern than a narrow array. This narrowing may be desirable in some instances, but it can also limit the number of low-frequency sound sources that can be effectively added to an array. This can be a problem where a wider or more consistent coverage pattern is desired without the detrimental effects of lobing, where there are dips and peaks in the response. Excessive narrowing may also occur when using a large curved array of speakers. In addition, an array may be inefficient and may not provide a great deal of useful off-axis attenuation—that is rejection directly behind the array. Therefore, there is a need for a sound source system that is capable of directing the coverage pattern with high SPL at low frequencies without the problem of narrowing the coverage pattern.